Take part in an underwater adventure in search of the mysterious Song of Dragons, which is said to be cursed...but also leads to a fabulous hidden treasure! Trek across the world with R&R Diving Service to exotic locales, including Pacific reefs, a South American river, sunken, shark-infested shipwrecks, the icy Antarctic and even in the inky black depths well below the Red Sea.

Endless Ocean: Blue World is the sequel to Endless Ocean, however, no experience with the previous game is necessary to play. You play as a diver looking for the Song of Dragons, and being recruited by R&R Diving Service, whose home base is on the small Nineball Island. Diving is very simple to control - simply point the Wii Remote at the screen and hold the B Trigger to swim. By aiming the pointer near the top, bottom, left or right of the screen, you'll change direction. The A Button is used to interact with fish, coral reefs, pick up objects and more. You can also use other tools such as fish food, a whistle, a multi-sensor (for salvaging items) and a camera.

The game features a main story to follow, but players can take it at their own pace, or decide to try some of the side-missions, such as dolphin training, filling an aquarium with fish to display, managing your private reef, mapping out areas you've visited and selling the maps for profit, salvaging treasure, pursuing special requests and treasure rumors, taking on photo requests for magazines, and even taking guided tours around locations you've already visited. Completing certain milestones in the game awards you "titles", which act as an achievement system. You can give yourself any title that you've unlocked to use as an identifier, and even mix and match them.

Endless Ocean: Blue World supports 2 player simultaneous multiplayer. Two divers can explore the ocean together, and send text messages to each other to communicate. If players have Wii Speak, they can talk to each other while diving as well. During online dives, main story quests cannot be completed and new creatures that you discover will not be recorded in your encyclopedia.